Die assembly



Oct. 26, 1965 D. OB 3,213,657

DIE ASSEMBLY Filed May a, 1964 s Sheets-Sheet 1 l2 GEORGE D. ROBE #rroeui/ DIE ASSEMBLY Filed May 8, 1964 I5 Sheets-Sheet 2 lfi/V'A'TOB ,47' Teams) G. D. ROBB DIE ASSEMBLY Oct. 26, 1965 3 Sheets-Sheet 3 Filed May 8, 1964 mvamoa.

GEORGE D. ROBB.

n/Kan ATTORNEY United States Patent 3,213,657 DIE ASSEMBLY George D. Robb, 21189 (Ioncord, Southfield, Mich. Filed May 8, 1964, Ser. No. 366,051 Claims. (Cl. 72-24) This application is a continuation-in-part of patent application Serial No. 314,792, filed October 8, 1963.

This invention relates to die assemblies and, in particular, to die assemblies which include workpiece lifters for raising the workpiece out of the die cavity after formation between the upper and lower dies.

At the present time, die sets employing large dies for forming workpieces of sheet material, such as sheet metal, have included various types of workpiece lifters installed in such dies and power-operated in unison to raise the formed workpiece out of the die cavity in the lower die after the upper die has been retracted upward, thereby permitting the workpiece to be withdrawn, either manually or by a mechanical device known in the automation art as an iron hand, after which a blank of sheet metal or the like is inserted in the space between the dies, and the press containing the dies is operated to form the next workpiece.

Hitherto, such workpiece lifters have been assembled from parts requiring special machining and not obtainable on the open market, hence causing such work lifter installations to be very expensive, both in cost of the parts and in installation. In such prior workpiece lifter installations, the units thereof had to be removed from the press and its lower die before the operating shafts could be properly machined and lined up, after which the units had to be reinstalled in the press and the shafts inserted. Moreover, such prior installations employed shafting mounted upon pillow blocks and carrying special pinions or gears, or carrying lifting arms or levers operating lifting plungers through a slotted connection therein.

The present invention provides a die assembly including conventional die halves, the stationary die half, having suitable openings therethrough to permit the movement of workpiece lifters between a forward position in which the lifters project into the space normally occupied by the formed workpiece, and a rear position in which the lifters are withdrawn from this space.

The workpiece lifting installation and workpiece lifters therefor make use primarily of commercially available parts manufactured in mass production and selling at relatively low prices. Moreover, the present invention provides lifting units which utilize stock shafting which can be drilled in place after the various units have been installed and drivingly connected to the units by roll pins, thereby eliminating the need for withdrawing the units in order to assemble the installation externally of the press and in order to mill keyways in the shafting and bearing surfaces thereon for insertion in the pillow blocks. Moreover, the present invention provides a workpiece lifting installation which can be mounted on a base plate or other support so as to constitute a package unit which can be assembled externally of the die and inserted in or removed from the die as a unit.

Accordingly, one object of the present invention is to provide a workpiece lifting installation and workpiece lifters therefor which utilize low-cost commercially available parts, can be assembled within or adjacent the die without disassembly for machining, and which can be mounted on a base plate or other support as a package unit which can be inserted in the die and removed therefrom as a unit rather than by removal of its individual components.

Another object is to provide a die assembly including 3,213,657 Patented Oct. 26, 1965 ice a workpiece lifting installation and workpiece lifters therefor which utilize hollow hubs or quills in the various lifters, thereby receiving stock shafting which can be drilled in place by a hand drill, using radial holes in the quill as guides, in order to receive roll pins which establish driving connections between the quills and the shafts.

Another object is to provide a die assembly including a workpiece lifting installation and workpiece lifter therefor, as set forth in the object immediately preceding, wherein the quills carry pinions keyed or otherwise drivingly connected thereto and meshing with vertical rack bars, constituting work lifting plungers, the whole being mounted in a casing or housing which also provides bearing support for the shafts and thus causes the lifting units to serve also as pillow blocks or bearing blocks for rotatably supporting the shafting.

Another object is to provide a die assembly having a workpiece lifting intsallation and workpiece lifter there for wherein the various workpiece lifting units are mountable with great versatility in different arrangements to adapt the installation to different production conditions, such as to lift different sizes, weights and shapes of workpieces from the die cavity.

Another object is to provide a die assembly having a workpiece lifting installation and workpiece lifter therefor, wherein the lifting units can be mounted in spaced parallel arrangement using spaced parallel shafts drivingly connected to one another in other than one-to-one ratio so that one set of lifting plungers moves faster upward than the other set, thereby tilting the workpiece as it rises, and facilitating the grasping thereof by an iron hand in an automation setup, such that the iron hand is not required to enter the space between the dies, so as to prevent serious damage to the dies by accidental closing of the dies while the iron hand is between them, as has occurred in prior installations.

Other objects and advantages of the invention will become apparent during the course of the following description of the accompanying drawings, wherein:

FIGURE 1 is a top plan view of the lower or stationary portion of a press with its lower die removed to reveal a workpiece lifting installation, according to one form of the invention, showing four workpiece lifters drivingly connected to one another for simultaneous actuation in order to lift the workpiece at four separate locations;

FIGURE 2 is a front elevation of the workpiece lifting installation shown in FIGURE 1, showing a workpiece being lifted thereby, but omitting the die and die cavity from which the workpiece is being lifted;

FIGURE 3 is an enlarged side elevation of one of the workpiece lifting units, with the driving shaft thereof in cross-section, looking in the direction of the line 3-3 in FIGURE 2;

FIGURE 4 is a front elevtaion, looking from the right in the direction of the arrows 44 in FIGURE 3;

FIGURE 5 is a horizontal section looking upward in the direction of the arrows 55 in FIGURE 3;

FIGURE 6 is a broken section taken along the oblique line 66 in FIGURE 3;

FIGURE 7 is a perspective view of a press, the workpiece being shown in phantom lines in raised position on the workpiece lifters; and

FIGURE 8 is a perspective view of the workpiece lifting installation and the workpiece lifters of FIGURE 7 with the entire press removed except for a supporting base plate.

Referring to the drawings in detail, FIGURES 1 and 2 show a workpiece lifting installation, generally designated 10, according to one form of the invention as including a base plate or mounting support 12 adapted to be mounted on the press (not shown) beneath the lower die thereof (also not shown). Mounted on the base plate or mounting support 12 in number and locations best adapted to the particular die from the cavity of which the workpiece W is to be lifted are a plurality of lifting units, generally designated 14, arranged in spaced parallel sets 15 and 17 respectively, drivingly connected to one another. Four such units 14 in two sets are shown, solely for purposes of exemplification, and not by way of limitation, as as greater or lesse rnumber of sets, or of units 14 per set, may obviously be used. Many large dies, such as those used for the production of automobile body stampings, will necessarily employ more than the four lifting units 14 and such units will be spaced farther apart than as shown in the drawing of the installation 10 in FIGURES 1 and 2. The units 14 in the installation 10 have been purposely placed close together so as to economize on space in the drawings and enable each lifting unit 14 to be shown on as large a scale as possible. The installation 10 is operated by a drive shaft 16 connected to any suitable actuator which will rotate the shaft 16 alternately in opposite directions. The actuator may consist of a rotary hydraulic motor wherein the shaft oscillates in either direction less than one revolution, of which several types are available on the market, a reciprocatory fluid pressure motor, the plunger of which reciprocates a rack meshing with a pinion on the drive shaft 16, or any other suitable means. FIGURES 7 and 8 show, for purposes of exemplification, one suggested orientation of the workpiece lifting installation, the workpiece lifters, and an actuator. This construction is described below in greater detail.

The drive shaft 16 is drivingly connected by a shaft coupling 18 to the input shaft 20 of the installation 10, the shaft 20 passing through and driving certain of the lifting units 14 in a manner described in more detail below following the description of the construction of the lifting unit 14 itself.

Each lifting unit 14 includes a housing structure, generally designated 22, which in turn consists of a pair of oppositely-facing housing halves 24 and 26 containing cavities 28 and 30 respectively which in cooperation form a pinion chamber 32. The housing halves 24 and 26 meet along a junction plane 34 (FIGURE 5) and are bolted together at this plane by through bolts 36. The housing halves 24 and 26 are provided with aligned bores 38 and 40 (FIGURE 5) in which a tubular spindle or quill 42 is rotatably mounted. The quill 40 for satisfactory bearing performance is conveniently made of bronze and is provided with diametrically-aligned holes 44 which in turn are aligned with a diametral hole 46 in the shaft 20. The

quill 42 is slightly longer than the thickness of the housing structure 22 so that the end containing the aligned holes 44 projects beyond the housing structure 22 (FIGURE 5). Mounted in the holes 44 and 46 is a roll pin 48 in the form of a longitudinally-split tube of resilient metal, such as steel, which expands or contracts to tightly engage holes of slightly differing diameters. This construction enables manufacturing tolerances to be liberalized without introducing lost motion in the drive.

The quil or tubular spindle 42 within the chamber 32 is provided with a recess or key seat 50 (FIGURE 6) in which is seated a Woodruff key 52 of segmental shape. The key seat 50 is preferably of arcuate shape because of the greater ease and lower cost of machining such a seat than of milling a longitudinal keyway in the tubular shaft 42. The key 52 engages an axial keyway 54 in a pinion 56 mounted within the chamber 32 and thereby drivingly connected to the quill or tubular shaft 42. The chamber 32 opens into a lateral chamber extension 58 having upper and lower bearing bores 60 of rectangular cross-section containing a reciprocable rack bar 62, the teeth 64 of which mesh with the pinion teeth 66. As a result of this construction, rotation of the shaft 20, transmitted to the quill 42 through the roll pin 48 is further transmitted through the key 52 to the pinion 56 and thence to the rack bar 62, reciprocating the latter. Lubricant is conveyed to the housing structure 22 by means of a lubricant fitting 68 threaded into the upper end of a lubricant passageway 70 in each housing half 24 and 26 and leading to the bore 40 whence it spreads along the outer surface of the quill 42 to the bore 38 and into the chamber 32 adjacent the pinion 56. The rack bar 62 at its upper end is provided with a threaded socket 72 (FIGURE 3) for connecting it to further motion-transmitting elements or to work-contacting heads 74 (FIGURE 2) preferably having rounded upper ends 76 for engagement with the workpiece W to be lifted from the mold cavity. The housing halves 24 and 26 near their peripheries are provided with aligned bores 78 and 80 to receive a roll pin 82 similar to the roll pin 48 and provided for the purpose of lining up the housing halves 24 and 26.

Each lifting unit 14 includes a pair of angle bars 84, the opposite arms of which are drilled as at 86 and 88. The holes 86 and 88 are spaced at distances suitable for spanning the distances between the bolt holes for the housing structure 22, the holes 86 being placed closer together than the holes 88 in order to use the angle bars for positioning the housing structure 22 and rack bar 62 in a vertical or inclined position. To position the rack bar 62 in a horizontal position by using the bolts 36 at the left-hand side thereof in FIGURE 3, the wider-spaced bolt holes 88 are employed to receive the bolts 36. In either case, the remaining bolt holes are used to receive hold-down bolts 90 (FIGURES l and 2) which pass through spacing plates 92 into the base plate or supporting plate 12.

Returning to the installation 10 (FIGURES 1 and 2), it will be seen that the input shaft 20 passes through the quills 42 of two aligned lifting units 14, which thereby serve as hearing blocks or pillow blocks for the input shaft 20. The quills 42 thus rotate in their respective bearing bores 38 and 40 to provide bearing support for the input shaft 20 and also in a similar manner for a countershaft 94 disposed with its axis in spaced parallel relationship to the axis of the input shaft 20. Pinned or otherwise secured, as at 96, to the shafts 20 and 94 are the hubs 98 of driving and driven gears 100 and 102 re spectively shielded by an inverted box-shaped sheet metal guard structure 103. The gears 100 and 102 are ordinarily of the same number of teeth so as to set up a driving ratio of one to one. This causes the rack bars 62 and their contact heads 74 to rise at equal rates, thereby causing the workpiece W to rise through successive parallel planes.

In certain installations, however, it is preferable to tilt the workpiece W as it is being lifted from the mold cavity, whereupon the gears 100 and 102 are made with different numbers of teeth so that the different pairs of rack bars 62 rise at different rates. Such tilting of the workpiece is used occasionally in an automation setup where it is desired to use an iron hand to reach in and grasp the workpiece. The tilting arrangement enables the iron hand to grasp the workpiece without the necessity of its reaching into the die cavity. In such an installation, the danger is eliminated of damaging the dies by colliding with the iron hand in the event that the dies are accidentally closed while the iron hand is within the space between the upper and lower dies. Such accidents have amounted to damages to the dies involving thousands of dollars, particularly in the case of automobile body panel dies.

The shaft 94 is drivingly connected to the quills 42 of its respective lifting units 14 by roll pins 48 in the manner described above for the input shaft 20, its lifting units 14 are identical with those driven by the input shaft 20 except that its rack bars 62 are moved away from the rack bars 62 of the opposing pair of lifting units 14 in order that rotation of the gear 102 in the opposite direction from the gear 100 will still cause the rack bars 62 driven thereby to rise or fall in unison with the rack bars 62 of the pair of lifting units 14 directly driven by the input shaft 20.

The mounting of the installation beneath the die cavity of the lower die depends, of course, upon the nature and shape of the die cavity and the workpiece formed therein. As will be shown below with respect to FIG- URES 7 and 8, the lower die member is provided with a series of vertical bores in horizontally-spaced locations best adapted for the most eflicient and practical ejection of the workpiece, and disposed in sets with each set containing a plurality of such bores so arranged that the rack bars 62 will rise and fall smoothly through these bores. The bores of each set are also arranged so that the horizontal bearing bores 38 and 40 of each housing 22 will be coaxial. When this relationship has been established, the base plate 12 is drilled to propertly locate the bolts 90, after which the bolts are inserted through the angle bars 84 and spacing bars 92, thereby firmly bolting down the housings 22 to the base plate 12. This arrangement causes the quills 42 of each set of lifting units 14 to become arranged coaxially.

The workman, without unbolting the housings 22 from their places upon the base plate 12, which has meanwhile been bolted or otherwise secured to the press bed (not shown), inserts shaft sections 20 and 94 of ordinary cold rolled shafting, out to proper lengths, through the thus aligned tubular spindles or quills 42, at the same time passing the shafts 20 and 94 through the bores in the hubs 98 of gears 100 and 102 placed between the lifting units 14 of the particular set. It will be understood, of course, that the housings 22 of the difierent sets of lifting units 14 are mounted at the proper distances apart from one another to cause the gears 100 and 102, when mounted on their respective shafts 20 and 94, to intermesh properly in a correct driving relationship. Using the holes 44 in the tubular spindles 42 as guides, and with the shafts 20 and 94 in place, the workman drills the holes 46 in the shafts 20 and 94 and also the holes for the pins 96 in the gear hubs 98 of the gears 100 and 102. He then inserts the roll pins 48 and 96 in their proper holes, thus drivingly connecting the tubular spindles 42 to the shafts 20 and 94 and also drivingly connecting the intermeshing gears 100 and 102 to the same shafts 20 and 94. The shaft coupling 18 is then installed upon the shaft 20 and the driving shaft similarly installed in the coupling 18 and connected to the driving or shaft oscillating mechanism (not shown).

In the operation of the workpiece lifting installation 10, let is be assumed that the upper and lower dies (not shown) have closed upon a sheet metal blank which is thereby converted into a formed workpiece W, whereupon the upper die of the die set is retracted upward. To eject the workpiece W from the die cavity, power is applied to the driving shaft 60 to rotate it a sufiicient distance in one direction to cause the subsequent rotation of the pinions 66 and power transmission gears 100 and 102 in such a manner as to cause the rack bars 62 to rise in predetermined timed relationship with one another, pushing the workpiece W upward out of the die cavity. The workpiece W is then removed, either manually by a workman or mechanically by an iron hand or similar grasping and transferring mechanism, and replaced by another blank. The shaft 16 is then rotated in the reverse direction to cause the rack bar 62 to descend, causing the caps or heads 74 to move downward in their respective die bores below the level of the bottom of the die cavity. The pressing operation is then repeated and the newly formed workpiece W then lifted and withdrawn in the same manner as described above.

It is desired to tilt the workpiece while lifting it from the die cavity, as described above in connection with the construction of the invention, the gears 100 and 102 are chosen with the differing numbers of teeth necessary to provide the proper lifting relationship between the different sets of lifting units 14 so that the tilting will occur in timed relationship. The tilted workpiece is then removed either manually or by an iron hand or other grasping and transferring mechanism in the manner described above. As previously stated, the tilting position of the workpiece is sometimes preferred in order to enable the iron hand to grasp the workpiece without entering the space between the upper and lower dies, so that if these are accidentally closed upon one another, no damage to the dies will occur by being moved together while the iron hand is between them.

FIGURES 7 and 8 show, for purposes of exemplification only, a press constructed in accordance with the present invention. The press of FIGURE 7 is intended to be representative only of either a mechanical or hydraulic press. The press generally indicated at 110, includes upper and lower die halves, respectively 112 and 114, the lifting installation and workpiece lifters being mounted below the lower die half 112.

As shown in FIGURE 7, the ram 116 of the press is movable vertically along a series of guide rods 118, thereby varying the position of the attached upper die half 114 with respect to the lower die half 112 fixed to the stationary bed 120 of the press 110. The actuating system for the ram 116 is disposed within a stationary housing 121 at the upper end of the press.

The workpiece lifting mechanism is shown as being situated within the press bed 120. FIGURE 8 shows the construction of this lifting mechanism wherein a hydraulic cylinder 122 produces a reciprocal linear movement of an actuating rod 124. The latter member includes a collar 126 which is fixed to a yoke 128 rigidly fastened to the center of a rack bar 130. At each of its ends, the rack bar 130 fits through the interior of a lifting unit 132 and engages the teeth of the pinion 56 in the same manner as illustrated in FIGURE 3.

The hydraulic cylinder 122 is actuated through fluid lines 134 and 136 which receive fluid from feed line 140 and discharge fluid to sump line 141 through a two-way spring-loaded valve 138. Actuation of the valve 138 induces a linear motion of the rod 124 and hence of the rack 130. This movement of the rack induces a rotational motion of the pinions 56 and hence of a horizontal shaft 142 which is fixed to the interior of each pinion 56 by means of roll pins 48 in the same manner as discussed above.

The opposite end of each shaft 142 is mounted within the pinion 56 of a lifting unit 132 mounted directly below the lower die half 112. Rotation of the shaft 142 causes the pinion 56 to vertically advance or retract a vertical rack bar 62. The upper end of each bar 62 includes a rubber roller 144. Openings 146, provided in the lower die 112 directly above the rollers 144, permit the rollers and racks to project therethrough when the racks are in their advanced or upper position. When the dies 112 and 114 are actuated to form a workpiece disposed therebetween, the workpiece will remain in the cavity of the lower die after the die halves are separated. If the lifting mechanism is actuated to move the racks 62 upwardly through the openings 146, the rollers 144 will abut the lower surface of the workpiece and raise it off of the die 112, at which time it is removed, either manually or mechanically by an iron hand or similar grasping and transferring mechanism.

The entire system, including the lifting units and the hydraulic equipment, is'mounted on a base plate 12 which is rigidly fixed in place in the bed 120 of the press. The plate may be removably mounted to permit repairs and adjustments to be made externally of the press.

The position of the two-way valve 138 which actuates the hydraulic cylinder 122, is controlled by energization of a simplified electrical circuit indicated at 148. This circuit is intended to be representative only. A limit switch is mounted along the lower surface of the press housing 121 and is actuated when the ram 116 is raised to its uppermost position. The limit switch, in-

dicated at S in FIGURE 8, completes the circuit 148 when it is closed, thereby actuating relay R which locks relay R closed, and shunts the current through line 154 and normally closed switch S when the ram descends and opens switch S The switch S is adapted to be opened by suitable means (not shown) when the iron hand or other transfer mechanism (also not shown), completes its grasping and removing operation on the formed workpiece.

In operation, with the ram 116 in its upper position the switches S and S are closed, thereby energizing and locking relay R and actuating the valve 138 so as to move the racks 62 upwardly and lift the workpiece out of the cavity of the female die. The iron hand (not shown) then advances, grasps and removes the Workpiece; as the iron hand withdraws, it opens the switch S which in turn unlocks relay R This terminates current flow to the valve 138 as soon as the ram begins to descend and thereby opens switch S This de-actuation of the valve 138 produces a downward movement of the racks 62, thereby permitting the next workpiece to be inserted between the dies before the ram reaches the bottom of its stroke.

Various other actuators and appropriate circuitry could obviously be employed to achieve the desired results. Whether the workpiece lifting equipment is to be actuated directly by the motion of the press, geared from the press drive, or driven by its own independent system, is a matter of choice and will depend on various factors including the type of press, the workpiece to be formed, the speed of operation, and many others.

It will be apparent to those skilled in the art to which this invention pertains, that various changes or modifications in the construction of the component parts may be made without departing from the spirit of the invention or from the scope of the appended claims.

Having thus described my invention, I claim:

1. A die assembly comprising in combination:

(a) a first stationary die half;

(b) a second die half movable with respect to said first die half, said die halves adapted when closed, to form a workpiece disposed therebetween;

(c) a base structure fixed with respect to said first die half and displaced from a space normally occupiedby said workpiece;

(d) a plurality of hollow workpiece-lifter housings secured to said base structure in spaced relationship and having coaxial bearing bores therein;

(e) a hollow spindle rotatably mounted in the bearing bores of each housing;

(f) a pinion drivingly connected to each spindle within its respective housing;

g) a toothed rack member reciprocally mounted in each housing in meshing engagement with its respec-v tive pinion;

(h) a shaft extending through at least one of said hollow spindles into another of said hollow spindles;

(i) and means connected to said die half and drivingly connecting said shaft to said hollow spindles so as to reciprocate said rack member between a first position wherein a portion of said rack member pro-" jects into the space between said closed dies normally occupied by said formed workpiece, and a second position, wherein said rack member is withdrawn from said space, said reciprocation occurring in timed relation to the motion of the die half.

2. A die assembly, according to claim 1, wherein said spindles and said shaft have aligned substantially diametral holes therein, and wherein tubular roll pins are drivingly seated in said aligned holes.

3. A die assembly, according to claim 1, wherein said bearing bores constitute substantially the sole bearing support for said shaft.

4. A die assembly, according to claim 1, wherein said rack members are disposed in spaced substantially parallel relationship.

5. A die assembly, according to claim 1 wherein sensing means are provided adapted to sense the relative position of said die halves and wherein said shaft is driven in response to said sensing means.

References Cited by the Examiner UNITED STATES PATENTS 629,658 7/99 Cargill 254-89 928,609 7/09 Klocke 11350 1,085,207 1/14 Irby 254-89 1,322,978 11/19 Verderber 254-89 1,612,994 1/ 27 Strid 74422 2,407,855 9/46 Stephens 1l350 2,648,247 8/53 Schmuziger 308-237 CHARLES W. LANI-IAM, Primary Examiner. 

1. A DIE ASSEMBLY COMPRISING IN COMBINATION: (A) A FIRST STATIONARY DIE HALF; (B) A SECOND DIE HALF MOVABLE WITH RESPECT TO SAID FIRST DIE HALD, SAID DIE HALVES ADAPTED WHEN CLOSED, TO FORM A WORKPIECE DISPOSED THEREBETWEEN; (C) A BASE STRUCTURE FIXED WITH RESPECT TO SAID FIRST DIE HALF AND DISPLACED FROM A SPACE NORMALLY OCCUPIED BY SAID WORKPIECE; (D) A PLURALITY OF HOLLOW WORKPIECE-LIFTER HOUSINGS SECURED TO SAID BASE STRUCTURE IN SPACED RELATIONSHIP AND HAVING COAXIAL BEARING BORES THEREIN; (E) A HOLLOW SPINDLE ROTATABLY MOUNTED IN THE BEARING BORES OF EACH HOUSING; (F) A PINION DRIVINGLY CONNECTED TO EACH SPINDLE WITHIN ITS RESPECTIVE HOUSING; (G) A TOOTHED RACK MEMBER RECIPROCALLY MOUNTED IN EACH HOUSING IN MESHING ENGAGEMENT WITH ITS RESPECTIVE PINION; (H) A SHAFT EXTENDING THROUGH AT LEAST ONE OF SAID HOLLOW SPINDLES INTO ANOTHER OF SAID HOLLOW SPINDLES; (I) AND MEANS CONNECTED TO SID DIE HALF AND DRIVINGLY CONNECTING SAID SHAFT TO SAID HOLLOW SPINDLES SO AS TO RECIPROCATE SAID RACK MEMBER BETWEEN A FIRST POSITION WHEREIN A PORTION OF SAID RACK MEMBER PROJECTS INTO THE SPACE BETWEENM SID CLOSED DIES NORMALLY OCCUPIED BY SAID FORMED WORKPIECE, AND A SECOND POSITION, WHEREIN SAID RACK MEMBER IS WITHDRAWN FROM SAID SPACE, SAID RECIPROCATION OCCURRING IN TIMED RELATION TO THE MOTIOIN OF THE DIE HALF. 